Using both quantitative and qualitative approaches, this study investigates the collocational errors in compositions written for the HSK (The Chinese language proficiency test) by American learners of Chinese. The results show that the vast majority of collocational errors are “verb + noun” collocations, and most of these errors are caused by the use of incorrect verbs. The main factors that caused these errors are also analyzed. The analysis shows that the misuse of synonyms, as well as orthographically and phonologically similar words, is the leading cause of the errors. The negative transfer of the learners’ mother tongue is also found to be a relatively important factor. Lastly, the study suggests that learners should be led by the teacher to notice collocations in texts, and then learn to construct collocation patterns on the basis of the analysis of the semantic features of most frequent words that collocate with the head words. The grasp of collocation patterns and the ability to generalize to more abstract patterns are some useful strategies to improve the outcomes of the teaching of vocabulary.